Beagle Pointing the Mars Way

ESA Mars Express probe is scheduled to arrive at Mars at Christmas : the Beagle 2 lander is expected to touch down on the surface of the Red Planet during the night of 24 to 25 December.

Launched on 2 June 2003 from Baikonur (Kazakhstan) on board a Russian Soyuz operated by Starsem, the European probe – built for ESA by a European team of industrial companies led by Astrium – carries seven scientific instruments that will perform a series of remote-sensing experiments designed to shed new light on the Martian atmosphere, the planet’s structure and its geology. In particular, the British-made Beagle 2 lander will contribute to the search for traces of life on Mars through exobiology experiments and geochemistry research.

On board Mars Express tests have been run to check that the instruments are functioning correctly. Mars Express has successfully come through its first power test on the whole spacecraft after the gigantic solar flare on 28 October. Since 17 November the onboard software has been ‘frozen’ after several updates and the spacecraft is now quietly proceeding to its destination.

Before even entering into Martian orbit to perform its mission, Mars Express has to face another challenge: safely delivering the Beagle 2 lander to its destination. This task, starting on 19 December, will not be without risk.

The early fiery entry of Beagle 2 probe into the thin Martian upper atmosphere at 12,000 miles per hour Credit: ESA

First of all, to deliver the lander where planned, Mars Express has been put on a collision course with Mars, since Beagle 2 does not have a propulsion system of its own and must therefore be ‘carried’ precisely to its destination. This means that after separation, Mars Express has to veer away quickly to avoid crashing onto the planet.

The landing site for the European rover called Beagle 2 lies on the floor of a large impact basin in the northern hemisphere of Mars. The name of the site, Isidis Planitia, refers to the broad, relatively flat plain that covers the floor of an extremely ancient, large basin formed by an asteroid or comet impact perhaps more than 4 billion years ago.

During the cruise Beagle 2 will take its power from the mother spacecraft, Mars Express. After separation and until its solar arrays are fully deployed on the surface, Beagle 2 must rely on its own battery, which cannot last beyond 6 days. So, like a caring parent, Mars Express must release Beagle 2 at the last possible moment to ensure that the lander has enough power for the rest of its journey to the surface.

Only then can Mars Express change its orientation and rapidly fire the thrusters to get away from the collision course and enter into orbit around Mars. This will be the first time that an orbiter delivers a lander without its own propulsion onto a planet and attempts orbit insertion immediately afterwards.

Since all these maneuvers are time-critical and allow little margin of error, the ground control team has had to simulate all possible scenarios (including glitches and problems, on board and on the ground) to make sure that nothing is left to chance.

The team has been training since September in a very realistic setting, using the same computers and equipment that will be employed during this mission phase. Although the real spacecraft cannot be directly involved, its behaviour is simulated via a sophisticated computer programme, using the actual flight software. These rehearsals, each lasting a day or more, cover all possible situations from the failure of an onboard instrument to the outbreak of a fire in the control room. One of these simulations will take place during the press conference on 3 December.

In this image of Mars, drainage networks are seen to feed into a larger river system. Credit: NASA

ESA‘s ground control team at ESOC, on the other hand, are having a very busy time. They are actively rehearsing responses to any situation that might arise when Mars Express releases Beagle 2 and enters into orbit around Mars. "The Mars Express mission is pushing the operations staff to extremes. Over the years, the experience acquired with experimental missions has provided a solid basis on which to prepare for the unexpected. The satellite controllers will rise to this new challenge", Gaele Winters, ESA Director of Technical and Operational Support, said.

Employing seven major instruments for its on-the-spot analyses, Mars Express will be able to identify signs of water in liquid, solid, or vapour form on Mars. Its lander will take a good chemical and morphological look at its landing site, looking for water in the soil, on rocks, and in the Martian atmosphere. It will investigate the existence of carbonate minerals and organic residues to detect possible signs of past or present life.